how do the door locks work?

[hoppo4.2]

More specifically how is the car unlocked?

from what i can find so far- the alarm sends an earth/ground trigger to pin B3 on plug j45 of the door ECU. I can replicate this with a test probe and the windows go up and the door release buttons stop working.

now this is where it gets interesting- everything ive read says that pin B3 is 12v all the time that the car is locked. but on mine its 12v all the time locked or open.

once locked what signal unlocks the car? other than triggering one of the internal door buttons nothing works.

My little project currently hasn't got a working alarm so interested to see how it should work

[Luckyone]

Had you seen this thread?

https://www.pistonheads.com/gassing/topic.asp?h=0&f=6&t=2015699

I was fiddling with the unlock a bit too out of interest, but gave up because it wasn't broken & I didn't want to make more work for myself!

One of our Cerbs has a different alarm, the non TVR specialist who fitted it was stumped by the unlocking part for a bit, he used a door lock motor to translate the signal lock / unlock signal from a normal alarm in to TVR language, I think he said those motors also acted as a switch....

[hoppo4.2]

I'd love to see a pic of that set up. if nothing else just to get my head round how the signal works

[Luckyone]

hoppo4.2 said:

I'd love to see a pic of that set up. if nothing else just to get my head round how the signal works

Sorry I doubt this is much help really:


I took one look at what he'd done & wished I'd just got a proper Meta alarm instead, mind you that was 10 years ago & it still working at the moment...

I was thinking of seeing exactly what he'd done but I've always got something more pressing to do.

As I understand it normal car alarms give a pulsed output to move the door locks one way or the other, the Cerb needs a permanently latched signal so he used the door motor from a normal car to give the permanently latched signal.

I'm guessing what your next question would be, sorry I don't know what type of door lock motor he used.

[hoppo4.2]

well that's different. but still makes no sense. if you find time i'd love to see how its wired up?

There is only 1 pin from the alarm to the door ECU- everything i can find says that that pin is supplied 12v while locked.

however that pin has around 11v on my car at all times. if you pulse that pin to ground it locks the car but the alarm pin B£ is still showing the same voltage when locked.

a second ground pulse doesn't unlock the car neither a 12v feed? so I'm stumped at this point as to how it should actually work